March 23, 2012 (Geneva) – The United Nation's World Meteorological Organization, representing 183 member nations, issued its Annual Statement onthe Status of the Global Climate today. The report concludes that climate change accelerated in the past decade and that 2011 was the 11th warmest year since records began in 1850.
Increasingly destructive tornadoes, floods and other indicators of global warming are also occuring with heightened frequency around the world. The new study found extreme weather events increased from 2001 to 2010 at an alarming rate consistent with global climate change. Worldwide, this included an increase in floods by 63%, drought 43%, heat waves 43%, heavy rain 43%, fires 25%, and tropical cyclones 24%.
[New paper by Kevin Trenberth] Framing the way to relate climate extremes to climate change
The average anthropogenic climate change effect is not negligible, but nor is it large, although a small shift in the mean
can lead to very large percentage changes in extremes. Anthropogenic global warming inherently has decadal time scales and
can be readily masked by natural variability on short time scales. To the extent that interactions are linear, even places
that feature below normal temperatures are still warmer than they otherwise would be. It is when natural variability and climate
change develop in the same direction that records get broken. For instance, the rapid transition from El Niño prior to May
2010 to La Niña by July 2010 along with global warming contributed to the record high sea surface temperatures in the tropical
Indian and Atlantic Oceans and in close proximity to places where record flooding subsequently occurred. A commentary is provided
on recent climate extremes. The answer to the oft-asked question of whether an event is caused by climate change is that it
is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer
and moister than it used to be.
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